<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<script>
			var num1 = parseInt(prompt("请输入第一个数"));
			var ope = prompt("请输入一个运算符号");
			var num2 = parseInt(prompt("请输入第二个数"));
			switch(ope) {
				case "+":
					alert(num1 + num2);
					break;
				case "-":
					alert(num1 - num2);
					break;
				case "*":
					alert(num1 * num2);
					break;
				case "/":
					alert(num1 / num2);
					break;
				default:
					alert("输入错误！");
					break;
			}
		</script>
	</body>

</html>